Add wget/curl fallback for vendor and update downloads

iso/overlay/usr/local/bin/bee-update.sh

@@ -12,6 +12,21 @@ TMP_BIN="/tmp/bee-audit-new"
 TMP_SIG="/tmp/bee-audit-new.sig"
 REPO_API="${BEE_RELEASE_API:-https://git.mchus.pro/api/v1/repos/<org>/bee/releases/latest}"
 
+download_to() {
+    url="$1"
+    out="$2"
+    if command -v wget >/dev/null 2>&1; then
+        wget -q -O "$out" "$url"
+        return $?
+    fi
+    if command -v curl >/dev/null 2>&1; then
+        curl -fsSL "$url" -o "$out"
+        return $?
+    fi
+    log "neither wget nor curl available"
+    return 1
+}
+
 version_of() {
     "$1" --version 2>/dev/null | head -n1 | tr -d '[:space:]'
 }
@@ -65,8 +80,8 @@ check_network_update() {
         return 1
     fi
 
-    if ! command -v wget >/dev/null 2>&1; then
-        log "wget not found; skip network update"
+    if ! command -v wget >/dev/null 2>&1 && ! command -v curl >/dev/null 2>&1; then
+        log "neither wget nor curl found; skip network update"
         return 1
     fi
     if ! command -v jq >/dev/null 2>&1; then
@@ -75,7 +90,7 @@ check_network_update() {
     fi
 
     meta="/tmp/bee-release-latest.json"
-    wget -q -O "$meta" "$REPO_API" || { log "failed to fetch release metadata"; return 1; }
+    download_to "$REPO_API" "$meta" || { log "failed to fetch release metadata"; return 1; }
 
     tag=$(jq -r '.tag_name // empty' "$meta")
     [ -n "$tag" ] || { log "release metadata missing tag_name"; return 1; }
@@ -90,8 +105,8 @@ check_network_update() {
     sig_url=$(jq -r '.assets[]? | select(.name=="bee-audit-linux-amd64.sig") | .browser_download_url // empty' "$meta")
     [ -n "$bin_url" ] && [ -n "$sig_url" ] || { log "missing release asset URLs"; return 1; }
 
-    wget -q -O "$TMP_BIN" "$bin_url" || return 1
-    wget -q -O "$TMP_SIG" "$sig_url" || return 1
+    download_to "$bin_url" "$TMP_BIN" || return 1
+    download_to "$sig_url" "$TMP_SIG" || return 1
     chmod +x "$TMP_BIN"
 
     log "network update candidate: $tag"